"The number of concealed handgun permits exploded during the Obama presidency," said John Lott Jr., the center's president, according to the Washington Examiner.

Lott said there were 4.6 million concealed handgun permit holders in 2007, and now that number is over 14.5 million. The increase has been steady throughout Barack Obama's presidency, by about 240,000 new permits each year.

The research center's report noted that 1.73 million more permits were issued than in the previous year. A little over 6 percent of the U.S.'s total adult population now has a permit.

The report said that in ten states, more than 10 percent of adults have concealed handgun permits. Indiana has the most residents who hold concealed carry permits, at 15 percent of the population. South Dakota is second at 14.7 percent.

Three states — Florida, Pennsylvania, and Texas — have over a million residents who actively hold concealed carry permits.

In eleven states, a permit is not required to carry in all or most of the state. The growth in permits does not paint a full picture of the rise in concealed carry permits because of that, according to the center's report.

More women are becoming permit holders. In states that gave out data according to gender, the number of women with permits has grown twice as quickly as the number of men.

The report pointed out that concealed carry permits are rising about 75 percent faster among minorities than among whites.

The center said that murder rates fell from 5.6 per 100,000 people to 4.7 per 100,000 during the time from 2007 to 2015, a decrease of 16 percent.

The Daily Caller found in the report that permit holders are convicted of felonies and misdemeanors at less than one-sixth the rate of police officers.